Recently, scientists have had to revise not only the well-established ideas about the physics of space and the Earth, but also about how life developed on Earth, what evolutionary stages it overcame, what forms it acquired on the way to the present state. The discoveries of paleontologists and geneticists are amazing - it turns out that much of what was previously considered an immutable truth has nothing to do with reality.
Age of life
Previously, it was believed that the very first and extremely primitive forms of life appeared on Earth about 2.5 billion years ago, and until then there was a purely chemical evolution, when the simplest molecules were combined into more complex chains.
This dating was revised several times - the moment of the formation of the first forms of life was pushed back further into the past, in those days when there was no oxygen atmosphere on Earth, thousands of volcanoes were active, the rocky soil of the continents was hot, and the average annual temperature fluctuated around + 60 ° FROM.
And in April last year, scientists reported that very active life existed on Earth already 3.5 billion years ago. A team of researchers from Norway, the United States and South Africa have discovered the oldest traces of life on Earth. Scientists have studied in detail samples of basalt glass mined in the so-called Middle Archean greenstone belt of South Africa and which are 3.5 billion years old. The samples were found to contain the thinnest tubes enriched with the elements necessary for life: carbon, nitrogen, phosphorus and potassium.
The authors of the discovery believe that these tubules in basalt glass are formed during the vital activity of bacteria. In similar breeds of later origin, traces of DNA were found in the same tubules. The age of the tubules is confirmed by the fact that they are partially destroyed during the growth of ancient metamorphic minerals.
Thus, we can say that a billion years have passed from the beginning of the formation of the planet Earth to the emergence of a developed biosphere of unicellular beings, which is an insignificant period of time by cosmic standards. Again, the question is on the agenda: if the biosphere appeared so quickly, was it not brought in from the outside - with comets or meteorites?
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Mysterious creature
From time to time, the discovered fossils baffle scientists.
The remains of a very strange creature, 525 million years old, were discovered in China a long time ago and were first described in 1979. Then the creature was named Vetustodermis planus and was included in the category of annelids living in the marine environment.
The results of subsequent studies have repeatedly questioned this classification, suggesting other options - they tried to attribute the creature to arthropods or mollusks.
And now David Bottger and his colleagues at the University of Southern California have decided to renew the debate about Vetustodermis - he believes that this creature may belong to a completely separate, unknown group, which flourished and disappeared within the Cambrian period. In fact, we are talking about a completely separate branch of evolution that has not received development in the modern era.
First animal
Do not lag behind their colleagues and scientists of the National Museum of Scotland. With the support of Yale University in the United States, they studied a tiny fossil found near Aberdeen in eastern Scotland for three years.
It turned out that these are the remains of the most ancient animal on the planet, of all the fossils ever found. This centipede a little more than a centimeter long ran across our planet 420 million years ago.
It is curious that this fossil was found by the Aberdeen bus driver Mike Newman, who is also a passionate hunter for ancient remains.
The author of the sensation himself did not know what he had dug up. This was understood only now by scientists who analyzed the find. In honor of Newman, the centipede was named Pneumodesmus newmani.
Scientists point out that if such a large air-breathing centipede lived on the planet, it means that at that time there were other animals and plants on the surface of the Earth that served it as food.
Here it should be noted that until recently, scientists believed that the first animals appeared and lived in the ocean 700 million years ago, and for the first time they crawled out onto land 250-300 million years ago. Accordingly, both of these dates should be revised.
Invasion of giant scorpions
At the time when land evolution was just beginning, it could have taken a completely different path.
Geologist Martin Whit of the British University of Sheffield has discovered fossilized footprints of a creature in Scotland that came ashore long before the earliest four-legged amphibians began to explore the land.
Traces were left 330 million years ago and this is direct evidence of the existence of an animal that came out of the sea to the shore.
But what creature has left footprints in the muddy, damp ground? Vita's analysis, published in November 2005, shows that these tracks belonged to a huge aquatic scorpion of the species Hibbertopterus.
Hibbertopterus and other aquatic scorpions became extinct 250 million years ago, even before the advent of dinosaurs. Modern land scorpions and some species of crabs are distant relatives of the ancient aquatic scorpions.
This creature was 1.6 meters long and 1 meter wide. Today's scorpions seem like pygmies against this background. The fossilized footprint itself is 6 meters long and 1 meter wide. It is the largest footprint of the species and the first to prove Hibbertopterus overland travel.
Studying the trail, Wit came to the conclusion that for a short time these giant scorpions could leave the sea. As long as their gills remained moist, they could easily breathe in the air.
The discovery raises the question: was the water scorpion the largest land-based predator of its time, terrorizing small land animals? Vit replies that no, because the Hibbertopterus was not equipped to attack ground creatures. Rather, they were the danger to him. The aquatic scorpion ate small marine organisms. And why he went out into the air remains a mystery.
Fortunately for terrestrial creatures, the giant scorpion was slow and could not stay on land for a long time. But if the coastal zone had not been inhabited at that time, who knows what the six-legged Hibbertopterus would have developed into?..
Beavers vs dinosaurs
Another well-established idea of paleontologists was the hypothesis that during the reign of the dinosaurs, mammals were small shy creatures and led a secretive lifestyle.
Imagine the surprise of Chinese scientists when they discovered a completely new species of an ancient animal - the fossilized remains of a mammal that lived 164 million years ago - that is, in the Jurassic period, in the heyday of the era of dinosaurs.
The creature, found in Inner Mongolia by paleontologists from the University of Nanjing, looks like it was assembled from several parts: there is something in its appearance from a platypus, something from an otter and a beaver.
The fur-covered Castorocauda lutrasimilis (as the prehistoric beaver was named) is the largest Jurassic mammal ever found. Its fur is the oldest of all previously discovered. The length of the animal is almost 0.5 meters (plus a 20-centimeter tail).
“It is also the earliest known mammal to have lived partly in water. He has developed limbs, a wide flat tail is adapted for active swimming, and his teeth are sharpened for fishing. „
The fossil found suggests that early mammals were much more diverse than was commonly believed. Castorocauda also showed that modern skin structures and warm-blooded metabolism developed in mammals very early - back in the days of the dinosaurs …